Field of the Invention
The present invention relates to a method of manufacturing a wiring substrate having a wiring layer including connection terminals, and to the wiring substrate.
Description of Related Art
In conventional manufacture of a wiring substrate, after a wiring layer including connection terminals is formed on a laminate of insulating layers and conductor layers, a solder resist layer is formed on the wiring layer and the laminate. Subsequently, openings are formed in the solder resist layer for exposing the connection terminals.
However, if the wiring layer differs from region to region in the density of disposition of wiring lines and the connection terminals, the formed solder resist layer differs in thickness from region to region. Specifically, in a region having a high density of disposition of the wiring lines and the connection terminals, the solder resist layer becomes thick, whereas, in a region having a low density of disposition of the wiring lines and the connection terminals, the solder resist layer becomes thin. Accordingly, the following faults arise: the connection terminals are not exposed from the openings formed in the solder resist layer; on the contrary, the connection terminals are excessively exposed such that the side surfaces of the connection terminals are completely exposed from the solder resist layer.
Meanwhile, in a conventionally proposed wiring substrate having no openings formed in the solder resist layer, dummy wiring lines are formed to lower the irregularities of the surface of the solder resist layer (e.g., Patent Document 1). Also, according to a conventionally proposed method of manufacturing a wiring substrate, after a mask having openings formed therein at positions corresponding to the connection terminals is formed on the solder resist layer, the solder resist layer is removed by wet blasting to expose the upper surfaces of the connection terminals (e.g., Patent Document 2).